- Education and Science
How to Make a Sundial, How Does a Sundial Work and Some Sundial History
Sundials aren't history
Many people think of sundials as nothing more than historical curiosities. How wrong can you be? Sundials are fantastic things to have in your garden, incredibly beautiful focal points just like any urn or garden sculpture.
But sundials are so much more too:
- Fascinating scientific instruments
- A link with history
- A surprisingly intimate way to personalize
- A connection to the universe
- A means to live life slower (and don't we all need that?)
Sounds over the top? Read on and find out just how interesting sundial are.
In this lens, you will find brief summaries of how sundials work and the history of sundials; information about famous sundials; pointers to instructions for how to make a sundial for kids young and old; ideas for how to use sundials in the garden; tips to help buy a sundial that really will tell the time; sundials to buy from ebay and sundial books to buy from Amazon. There are also links to more detailed information and lots of very pretty pictures of sundials!
Just to whet your appetite
There are loads of amazing sundials in the world. This is just a taster, with pictures of some of the most famous sundials, contemporary and from history, showing something of the huge diversity. Click on the sundials to see a larger photo on Flickr.
The Sundial Bridge
The beautiful Sundial Bridge spans the Sacramento River at Redding, California. The bridge is a working sundial: a 217 foot high fin casts a shadow on a huge garden-lined dial plate at the north end. For engineering reasons, it is not completely accurate. To see more photos, do a Flickr search - there are many fantastic photos of the Sundial Bridge.
Bewcastle Cross sundial
This is the oldest existing sundial in the UK. A vertical sundial is carved into a richly decorated Anglo-Saxon cross at Bewcastle in Cumbria, probably in the late seventh century. The sundial is the fan-shaped carving near the top of the photo. Another very early sundial (about 1050 AD) is carved above the door of St Gregory Minster in Yorkshire, England. You can see a photo here as well as some of the old English lettering that surrounds the sundial.
The Tower of the Winds
Built in the marketplace at Athens in around 50BC, the octagonal tower bears a relief sculpture of a wind god on each face. Underneath each sculpture is a sundial, each engraved differently for the direction.Thumbnail by Andreas Trepte, www.photo-natur.de
Huge equatorial sundial in Jaipur, India, built in the eighteenth century. The time is told from the shadow of a fifty-step staircase. Not particularily accurate.
Queens' College sundial
Elaborate early eighteenth century sundial at a Cambridge University college. As well as the time, this sundial shows the signs of the zodiac, the sun's altitude and direction, the time of sunrise and the length of the day. It also enables timetelling by moonlight. Read more about the Queens' college sundial. Photo by Throwawayhack.
General sundials links
These websites have information about all aspects of sundials.
- The North American Sundial Society
Sundials in the US, FAQs, forum, links.
- The British Sundial Society
Dials in the UK, glossary, links.
- Sundials pages from the National Maritime Museum, London
History and theory. Good readable summary.
- Wikipedia on sundials
Got to include them, right? You know the format. Solid technical information, bit indigestible.
How does a sundial work?
The basic idea is simple. A sundial has a pointer - called a gnomon - and the shadow cast by the gnomon when the sun shines follows a predictable path through the day. The path can be marked with hours to tell the time.
Sounds too simple? Well, it is a little bit more complicated than that.
The trouble is that the predictable shadow path changes through the year. There are two reasons for this:
- The earth follows an elliptical orbit around the sun
- The earth's tilted axis
As a result, the shadow cast by the gnomon moves at different speeds and to slightly different places at different times of the year. Dialists - sundial makers - call this "solar time".
Luckily, the difference between solar time and clock time can be corrected with maths. Dialists use angled gnomons and the "equation of time" to correct their sundials. See below for links to explanations of this.
There is a further correction that needs to be made if a sundial is to match clock time.
Modern time zones (for example the Greenwich Mean Time zone) tell the time for large areas. The shadow cast by the gnomon of a sundial tells the time for the exact position of the sundial.
So the hour lines on a sundial need to be adjusted so the shadow tells the time for its time zone instead of its exact position. Unless, of course, a sundial is set exactly on the Meridian.
That's the basics. But there is a lot more mathematical matter behind sundials. If you want to find out more, use the links below.
Find out more about how sundials work - Websites
The theory behind how sundials work is quite complicated. And a lot of the material out there is written by passionate dialists immersed in their subject and its jargon. This can be a bit hard to swallow. Persevere if you want to learn about sundials. It will make sense eventually.
- How sundials work
Very simple explanation, with pictures from the National Museums Liverpool, UK
- The Suntracker
Simple program which shows how the path of the sun changes at different times of the year and at different latitudes. Also from the National Museums Liverpool
- How do sundials work ?
Comprehensive but straightforward explanation of everything about how sundials work from the British Sundial Society. Lots of explanatory photos and graphics. An excellent resource.
- The Sundial Primer
Lots of information about how sundials work, different types of sundials and how to make them. Very mathematical.
Chronology of how time has been measured, including explanations of solar time.
Good explanations and animations of the earth's tilted axis and elliptical orbit.
Do you own a sundial?
Different types of sundials
This is not an exhaustive list. Just an outline of the main sorts of sundials.
Horizontal sundials: This is what most people think of as a sundial: a horizontal dial face with an angled gnomon, set in a pretty English garden.
They are pretty, but they are far from the end of the story.
Vertical sundials: Often attached to the side of a building, vertical sundials are, well, vertical. Historically, many were placed on churches. In the middle ages in Britain, sundials were literally scratched onto the walls of churches, probably to show the hours of church services. These scratch sundials (see this ancient example from Northamptonshire, UK) are a type of vertical sundial.
Equatorial sundials: These sundials have a dial plate that is tilted at an angle parallel to the equator. The gnomon is then set at right angles to the dial plate, parallel to the earth's axis. This is another way to solve some of the timetelling peculiarities caused by the tilt in the earth's axis.
Armillary sundials: A type of equatorial dial. In ancient times, armillary spheres were used to demonstrate the working of the solar system.
Modern versions are sundials, casting a timetelling shadow from a rod running through the centre of the sphere onto an encircling band.
Portable sundials: Mainly historical. The sundial equivalent of a watch.
Analemma: This unusual type of sundial does not tell the time, just the date. It works from the fact that if you marked the position of the sun in the sky every day for a year at, say, noon, you would trace out a figure of eight. The analemma shows this figure of eight, with markings for dates.
Sundials videos on YouTube
The first video shows very well how latitude affects sundial timetelling, and how setting the gnomon at an angle will make a sundial work correctly. The second video is an interesting historical look at time telling.
The MacDonald's billboard sundial video is a timelapse showing how the shadow cast by a gnomon moves across the face of a sundial, in this case to indicate which MacDonald product is best to buy at different times. The company searched far and wide for a billboard at the right angle to work as a sundial over breakfast hours. And it only worked for a few months! But the company received loads of publicity. The idea was replicated in an ad for the Dark is Deadly XBox game - see here.
The last video illustrates sundial artist David Harber's work in action.
Sundials in the garden
Think again if you thought that all sundials have to offer in the garden is an olde worlde horizontal piece in a flowery nook evoking a charming English country garden atmosphere.
In the garden, sundials are remarkably versatile and beautiful focal points.
Armillary spheres, for example, are elegant and refined statuary when made of bronze; made of stainless steel, they are glittering contemporary sculptures.
Armillary spheres also have the advantage of not hiding the vista beyond, so they can work well in smaller gardens.
A vertical sundial above the entrance to your home - perhaps with the house name engraved - gives visitors a memorable welcome. Vertical sundials can also cover up flaws in the wall behind.
Then there's garden obelisks - stunning dramatic features in any garden.
Though they cannot accurately tell the time (they have no gnomon), the shadow cast by an obelisk can mark dates. Ground markers can be inserted around an obelisk to indicate family birthdays, for example.
Which brings me to personalization, something sundials are particularly suited to. Mottoes are traditional on sundials. If you pick an appropriate one and combine it with significant date markers on the sundial's timetelling face, you have the most perfect and intimate wedding/anniversary/birthday gift imaginable.
"The only possibility in life as in love, is in growth, in fluidity in freedom in the sense that dancers are free, barely touching as they pass but patterns in the same pattern"
This touching quotation comes from a personalized sundial, an anniversary gift made by the celebrated dialist David Harber for his wife. Very romantic.
Being so particular to their own time and place, Sundials also lend themselves to personalization with dates and directions. This is another David Harber example showing the exact latitude and longitude of a sundial at the famous and very old St Paul's School in London, England.
Harber is a terrific current practitioner of sundials as garden art (or see his sundials website for the US or any Russian readers (?) can see www.davidharber.ru). His creations are accurate sundials of all kinds, with a specialism in armillary spheres as well as other garden items like water features. David Harber's sundials are also stunning garden art, often very contemporary, that puts paid to the notion that sundials are nothing but historical curiosities.
View some examples of David Harber's sundials below. You can also see his work on Facebook, Pinterest or Flickr.
Garden Art: David Harber's sundials
Below is a detail of a Moon Sundial by David Harber showing the pointers that mark the spot where the moon's shadow will hit the dial on the day of a full moon and the three days before and after when there is enough light for the moondial to function at night. The Moon Sundial is also a fully functional daytime sundial.
More David Harber sundials (click the photos to see them larger on Flickr or Pinterest):
At the famous
o'clock on a
Sundial project: make a sundial with your kids - Sundials for kids
Making a simple sundial is a good way to keep the kids away from the playstation for several hours if you help them. And if you complete the project, children do seem to remain interested.
Making a sundial is surprisingly easy and will teach your children a lot about how the solar system works. And creating a real working sundial is very satisfying for kids.
To make a horizontal sundial, all you will need are scissors, tape, heavy card and a compass. Oh and the sun of course!
There are loads of instructions on how to build a sundial on the web. Most of them have print-outs with the hour lines ready drawn to make things easy. There are also a few books suitable for kids. I have listed some of the best of both here.
How to make a sundial - websites:
- BBC make a sundial
Make a horizontal sundial: easy, aimed at kids, with photo instructions
- Make your own sundial from the National Maritime Museum, London
Another horizontal sundial to build, with print out instructions and template for the sundial base and gnomon. Nicely designed.
- Make a sundial necklace/keychain
The website isn't so pretty but the end result is good. Has three levels of difficulty so older kids can make a sundial base themselves with a protractor.
- How to make a sundial for your ceiling
A really fun idea - a long term project to turn the ceiling into a sundial by marking the position of the sun's reflection from a mirror. If you are artistic, the markings could then be painted for a really unusual and interesting room decoration. Spot dials like this are not uncommon in history, though typically they marked noon on the floor of churches.
- Sundial fryer
Another major build a sundial project: PDF instructions to make a sundial out of a frying pan! Not for the fainthearted, requires metalworking experience.
- Make your own vertical sundial
Also tricky: to make a vertical sundial - aka wall sundial - requires more maths than horizontal or equatorial dials. You need to know exactly where the dial is facing. The instructions are straightforward.
- Lego sundials
Not as easy as it sounds. Three tiny little sundials with instructions and large photos. Again, for older children
- Personalized sundial template from Google Maps
Not sure how well this works but it's a very cool idea
How to make a sundial - books:
For kids, this book is one of the best options. It is nice and simple, and does a lot of the work for you, with sundial templates on heavy card ready to cut out. Has templates for horizontal, vertical and equatorial sundials.
For a bigger project, how about a simple wooden sundial? Instructions for making several different types of sundials. Requires basic woodworking.
Just in case you fancy making a clock instead. Quite complicated and fiddly so for older kids only, unless you are prepared to do most of the cutting and sticking.
A more serious child's guide to sundials
If you would like to embark on some proper teaching, Make a Sundial is a guide published by the British Sundial Society originally as a school textbook. It is mainly for children under 11, but there are some projects to build a sundial for the older child. Details can be found near the top of the Books and Publications page of the British Sundials Society. The page also has details of many other sundial books and pamphlets,as well as booksellers who may stock rarer items.
History of sundials: ancient sundials
Sundials today are decorative and interesting. In history, they were also practical timetelling devices. This was true even after mechanical clocks appeared because clocks were inaccurate until the twentieth century. Sundials were needed to correct them.
Nobody knows who invented the sundial. The earliest existing sundial is Egyptian, from around 1500BC. The Greeks built on the primitive Egyptian ideas and developed accurate sundials, many in prominent places in the Greek Empire.
The Romans too built accurate sundials to tell the time. Shepherds carried small portable ones. An interesting practice, symbolic of Roman power, was transporting old Egyptian obelisks to Rome and setting them up as sundials in public places.
Much of this sundial expertise disappeared in the dark ages. When sundials reappeared, they were less sophisticated, with incorrectly angled gnomons and often marking the times of church services instead of what we think of as real time.
The Arabs rediscovered how to make accurate sundials in the late middle ages and this knowledge somehow (like much of Arabic expertise at this time, nobody is really sure how) made its way back to the West.
See below for what happened next.
Buy a Sundial Book at Amazon
Standard text on sundials.
Approachable advice on how to make sundials.
Beautiful coffee table book, but full of well researched information. A bit eclectic and impresionistic.
Guide to sundials in Britain. Fascinating historical information and photos. One too many pictures of the author's own sundials.
Fun for kids: human sundials
Making a human sundial is another major sundial project, but it does have lasting educational and play value.
The basic idea is that you create a sundial face on a large flat sunny area by painting or fixing time markers on the ground.
The gnomon is a person, standing in the center of the face, casting the shadow that tells the time. The photo illustrates the concept. Like all other sundials, each human sundial must be tailor-made to its own latitude and longitude.
Creating a human sundial can be as simple or as complicated as you choose. Crayola provides some easy instructions for a rough and ready human sundial suitable for quite young kids using trial and error and chalk.
By contrast, the human sundial in the photo (it's in New Mexico) is properly calibrated and is made with engraved stones set into the grass.
You can buy inexpensive kits that provide instructions for setting up a human sundial for your latitude and longitude.
The kits are popular with schools - this project requires a lot of work and spans a number of academic disciplines. But for parents more dedicated that I could ever be, this is an opportunity to create something beautiful and fascinating with your children.
If you are interested, Sunclocks in the UK is the major supplier for the Northern hemisphere - owner Douglas Hunt pioneered the idea. For the southern hemisphere, see human sundials in Australia.
Sundials for learning is a much newer supplier of what this company calls the Sundial of Human Involvement. The website is very helpful.
A clever idea - indoor sundials
Sundials need the sun so they have to be placed outdoors, right?
Nope, not with the Spectra sundial, a modern sundial that follows in the tradition of ingenious sundial making.
The dial is designed to sit on a windowsill or other sunny spot indoors and tell the time as it beams vibrant color into the room. All that is necessary is that it is rotated to face the proper direction and that it is placed in the sun.
So this sundial does still need the sun. But it does mean you and your children can enjoy the fascination of a sundial from inside the house.
History of sundials: modern times
The sixteenth to eighteenth centuries were the heyday of sundials. Although clocks existed, they lost time fast, so sundials were needed to correct them. Gnomonics, the study of sundials, was an important academic subject; and the craft of making scientific instrumentation developed by leaps and bounds. Powered by these factors, huge numbers of beautiful and accurate sundials of many different kinds were made all over Europe for both practical use and for decoration.
Amongst the sundials made during these centuries were:
Polyhedral dials: sundials built on mathematical solids, often beautiful and richly engraved. The picture shown is of a carved ivory polyhedral sundial from Hans Holbein's painting, The Ambassadors. Click on the photo to see a different metal example.
Pocket sundials: the boy's toys of yesteryear, showing readings not just of time but also date, compass direction, astrological information and more. Often exquisitely engraved ivory or brass with a flip top.
Scottish multiple dials: Unique to Scotland. Obelisk shaped structures smothered with sundials - 20, 30 and even 40 are not uncommon. Sundials were remarkably popular in Scotland in the seventeenth and eighteenth centuries. (See Sundials of Scotland). Interestingly, David Harber (see above) has brought the tradition to life again in a pillar sundial he created for Sunrise Senior Living in Wolverhampton, UK.
Gradually, as clocks became more accurate, sundials fell out of favour, although French railwaymen were reputedly still using them as late as 1900 to regulate the times of trains.
Recently, sundials have been undergoing another renaissance as decorative ornaments.
Find out more about the history of sundials
- Sundials in Medieval Islamic Science and Civilization
In the middle ages, sundial expertise flourished in the East rather than the West. This paper covers some of that history.
- Summary of sundial history
Good brief summary.
- Historical overview
Discusses the development of sundials from a practical perspective. Interesting examples.
Buy a sundial on eBay
As ever, be careful when buying from eBay. Common sense and a check of a sellers' reputation are always a good idea. And bear in mind the precautions specific to sundial mentioned below. But if you are simply looking for something pretty to go in the garden, there are good deals to be had...
What to watch out for when you buy a sundial
These tips only apply if you want to buy a sundial that tells accurate clock time.
If you are buying from a well-known sundial maker, there shouldn't be a problem anyway. But if you are buying a cheap horizontal dial, you need to be more careful.
Many cheap sundials are technically excellent. Others are not. You need to check:
- That the gnomon points to 12.00, or 1.00 if your sundial is set for summer time.
- That the gnomon is straight and simple. You can't read the time off a curvy shadow.
- That the gnomon has been set at an angle equal to your latitude if the dial is flat; or that the dial plate is set at an angle equal to your latitude with the gnomon set at a right angle to the dial plate.Sounds a bit complicated I know, but if the gnomon is set wrong, there is no way a simple sundial can tell the right time.
This page finds your latitude on a Google map. Or you can look it up on a map.
Slow down. Stop thinking about yourself
We all live too fast nowadays, right?
Put a sundial in your garden and you will find yourself drawn to watch it. Slowly. Because sundials don't move fast. Watch the timetelling shadow crawl across the dial face and feel the years slip away as you connect with an older, slower way of life.
You will also find yourself drawn to think about the heavens. How can you fail to once you understand that it is the earth's orbit around the sun that is telling the time? And seeing the earth as but a small part of our solar system is a salutary change of perspective from the customary "me me me" thinking of modern life.
I'm not saying a sundial will change your life. But a break from today's hectic pace of living has got to be a good thing.
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